/**
 * Copyright [2019-2022] [starBlues]
 *
 * Licensed under the Apache License, Version 2.0 (the "License");
 * you may not use this file except in compliance with the License.
 * You may obtain a copy of the License at
 *
 *        http://www.apache.org/licenses/LICENSE-2.0
 *
 * Unless required by applicable law or agreed to in writing, software
 * distributed under the License is distributed on an "AS IS" BASIS,
 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
 * See the License for the specific language governing permissions and
 * limitations under the License.
 */

package com.gitee.starblues.loader.jar;

import java.io.IOException;
import java.time.ZoneId;
import java.time.ZonedDateTime;
import java.time.temporal.ChronoField;
import java.time.temporal.ChronoUnit;
import java.time.temporal.ValueRange;

/**
 * copy from spring-boot-loader
 * @author starBlues
 * @version 3.0.0
 */
public class CentralDirectoryFileHeader implements FileHeader {

    private static final AsciiBytes SLASH = new AsciiBytes("/");

    private static final byte[] NO_EXTRA = {};

    private static final AsciiBytes NO_COMMENT = new AsciiBytes("");

    private byte[] header;

    private int headerOffset;

    private AsciiBytes name;

    private byte[] extra;

    private AsciiBytes comment;

    private long localHeaderOffset;

    CentralDirectoryFileHeader() {
    }

    CentralDirectoryFileHeader(byte[] header, int headerOffset, AsciiBytes name, byte[] extra, AsciiBytes comment,
                               long localHeaderOffset) {
        this.header = header;
        this.headerOffset = headerOffset;
        this.name = name;
        this.extra = extra;
        this.comment = comment;
        this.localHeaderOffset = localHeaderOffset;
    }

    void load(byte[] data, int dataOffset, RandomAccessData variableData, int variableOffset, JarEntryFilter filter)
            throws IOException {
        // Load fixed part
        this.header = data;
        this.headerOffset = dataOffset;
        long nameLength = Bytes.littleEndianValue(data, dataOffset + 28, 2);
        long extraLength = Bytes.littleEndianValue(data, dataOffset + 30, 2);
        long commentLength = Bytes.littleEndianValue(data, dataOffset + 32, 2);
        this.localHeaderOffset = Bytes.littleEndianValue(data, dataOffset + 42, 4);
        // Load variable part
        dataOffset += 46;
        if (variableData != null) {
            data = variableData.read(variableOffset + 46, nameLength + extraLength + commentLength);
            dataOffset = 0;
        }
        this.name = new AsciiBytes(data, dataOffset, (int) nameLength);
        if (filter != null) {
            this.name = filter.apply(this.name);
        }
        this.extra = NO_EXTRA;
        this.comment = NO_COMMENT;
        if (extraLength > 0) {
            this.extra = new byte[(int) extraLength];
            System.arraycopy(data, (int) (dataOffset + nameLength), this.extra, 0, this.extra.length);
        }
        if (commentLength > 0) {
            this.comment = new AsciiBytes(data, (int) (dataOffset + nameLength + extraLength), (int) commentLength);
        }
    }

    AsciiBytes getName() {
        return this.name;
    }

    @Override
    public boolean hasName(CharSequence name, char suffix) {
        return this.name.matches(name, suffix);
    }

    boolean isDirectory() {
        return this.name.endsWith(SLASH);
    }

    @Override
    public int getMethod() {
        return (int) Bytes.littleEndianValue(this.header, this.headerOffset + 10, 2);
    }

    long getTime() {
        long datetime = Bytes.littleEndianValue(this.header, this.headerOffset + 12, 4);
        return decodeMsDosFormatDateTime(datetime);
    }

    /**
     * Decode MS-DOS Date Time details. See <a href=
     * "https://docs.microsoft.com/en-gb/windows/desktop/api/winbase/nf-winbase-dosdatetimetofiletime">
     * Microsoft's documentation</a> for more details of the format.
     * @param datetime the date and time
     * @return the date and time as milliseconds since the epoch
     */
    private long decodeMsDosFormatDateTime(long datetime) {
        int year = getChronoValue(((datetime >> 25) & 0x7f) + 1980, ChronoField.YEAR);
        int month = getChronoValue((datetime >> 21) & 0x0f, ChronoField.MONTH_OF_YEAR);
        int day = getChronoValue((datetime >> 16) & 0x1f, ChronoField.DAY_OF_MONTH);
        int hour = getChronoValue((datetime >> 11) & 0x1f, ChronoField.HOUR_OF_DAY);
        int minute = getChronoValue((datetime >> 5) & 0x3f, ChronoField.MINUTE_OF_HOUR);
        int second = getChronoValue((datetime << 1) & 0x3e, ChronoField.SECOND_OF_MINUTE);
        return ZonedDateTime.of(year, month, day, hour, minute, second, 0, ZoneId.systemDefault()).toInstant()
                .truncatedTo(ChronoUnit.SECONDS).toEpochMilli();
    }

    long getCrc() {
        return Bytes.littleEndianValue(this.header, this.headerOffset + 16, 4);
    }

    @Override
    public long getCompressedSize() {
        return Bytes.littleEndianValue(this.header, this.headerOffset + 20, 4);
    }

    @Override
    public long getSize() {
        return Bytes.littleEndianValue(this.header, this.headerOffset + 24, 4);
    }

    byte[] getExtra() {
        return this.extra;
    }

    boolean hasExtra() {
        return this.extra.length > 0;
    }

    AsciiBytes getComment() {
        return this.comment;
    }

    @Override
    public long getLocalHeaderOffset() {
        return this.localHeaderOffset;
    }

    @Override
    public CentralDirectoryFileHeader clone() {
        byte[] header = new byte[46];
        System.arraycopy(this.header, this.headerOffset, header, 0, header.length);
        return new CentralDirectoryFileHeader(header, 0, this.name, header, this.comment, this.localHeaderOffset);
    }

    static CentralDirectoryFileHeader fromRandomAccessData(RandomAccessData data, int offset, JarEntryFilter filter)
            throws IOException {
        CentralDirectoryFileHeader fileHeader = new CentralDirectoryFileHeader();
        byte[] bytes = data.read(offset, 46);
        fileHeader.load(bytes, 0, data, offset, filter);
        return fileHeader;
    }

    private static int getChronoValue(long value, ChronoField field) {
        ValueRange range = field.range();
        return Math.toIntExact(Math.min(Math.max(value, range.getMinimum()), range.getMaximum()));
    }

}

